Abstract
Lead poisoning, mainly through incidental ingestion of lead ammunition in carcasses, is a threat to scavenging and predatory bird species worldwide. In Australia, shooting for animal control is widespread, and a range of native scavenging species are susceptible to lead exposure. However, the prevalence of lead exposure in Australia's scavenging and predatory birds is largely unknown. We evaluated the degree to which the Tasmanian wedge‐tailed eagle (Aquila audax fleayi), an endangered Australian raptor and facultative scavenger, showed evidence of lead exposure. We detected lead in 100% of femur and liver tissues of 109 eagle carcasses opportunistically collected throughout Tasmania between 1996 and 2018. Concentrations were elevated in 10% of 106 liver (>6 mg/kg dry wt) and 4% of 108 femur (>10 mg/kg dry wt) samples. We also detected lead in 96% of blood samples taken from 24 live nestlings, with 8% at elevated concentrations (>10 μg/dL). Of the liver samples with elevated lead, 73% had lead207/206 isotope ratios within the published range of lead‐based bullets available in Tasmania. These first comprehensive data on lead exposure of an Australian raptor are comparable to those for raptor studies elsewhere that identify lead‐based ammunition exposure as a conservation threat. Our findings highlight the importance of further research and efforts to address lead contamination throughout the Tasmanian ecosystem and in other Australian regions. Environ Toxicol Chem 2021;40:219–230. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.
Highlights
Lead is a toxic metal that can negatively affect a range of physiological systems, thereby threatening susceptible animal populations and ecosystems (Goyer and Clarkson 2001; Finkelstein et al 2012)
Lead exposure has been reported in 34 raptor species (Pain et al 2009, 2019), ingestion has been identified as the route of exposure (e.g., Katzner et al 2017), and the link between lead‐based ammunition and exposure is evidenced by increased lead concentrations in raptors during the hunting season (Kelly and Johnson 2011; Cruz‐Martinez et al 2012; Garbett et al 2018), isotopic similarities between lead in tissues and those of ammunitions (Finkelstein et al 2012; Ishii et al 2017), and the presence of lead ammunition in regurgitated pellets and the alimentary canals of a range of raptor species (e.g., Donázar et al 2002; Helander et al 2009)
There was no evidence of spatial organization in lead concentrations of liver (n = 71; multiple regressions on distance matrices (MRM): R2 = 0.003, F = 8.382, p = 0.393; Mantel: p = 0.721, r = –0.029), femur (n = 72; MRM: R2 = 0.001, F = 2.575, p = 0.574; Mantel: p = 0.473, r = –0.053), or nestling blood samples (n = 24; MRM: R2 < 0.001, F = 0.097, p = 0.898; Mantel: p = 0.68, r = –0.054)
Summary
Lead is a toxic metal that can negatively affect a range of physiological systems, thereby threatening susceptible animal populations and ecosystems (Goyer and Clarkson 2001; Finkelstein et al 2012). Clinical signs of lead poisoning include ataxia, impaired mobility, lowered sensorial ability, One of the ways that avian predators and scavengers are susceptible to lead poisoning is through the incidental ingestion of lead‐based bullet fragments (Fisher et al 2006; Golden et al 2016; Pain et al 2019). Lead exposure has been reported in 34 raptor species (Pain et al 2009, 2019), ingestion has been identified as the route of exposure (e.g., Katzner et al 2017), and the link between lead‐based ammunition and exposure is evidenced by increased lead concentrations in raptors during the hunting season (Kelly and Johnson 2011; Cruz‐Martinez et al 2012; Garbett et al 2018), isotopic similarities between lead in tissues and those of ammunitions (Finkelstein et al 2012; Ishii et al 2017), and the presence of lead ammunition in regurgitated pellets and the alimentary canals of a range of raptor species (e.g., Donázar et al 2002; Helander et al 2009)
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